JPH0814530B2 - Weather resistance test method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a weather resistance test method, and particularly in a weather resistance test of plastics, paints, inks, pigments, fibers, etc., the initial change is gradual and outdoor natural deterioration occurs. The present invention relates to a weather resistance test method capable of obtaining a test result having a very good correlation with.

[Conventional technology]

Conventionally, when measuring the weather resistance of a plastic material, a paint, or the like, a weather resistance tester according to JIS B7751 to 7754 is generally used. These testers usually use a light source such as a carbon arc lamp or a xenon arc lamp, and irradiate the sample with light from the light source to perform a weather resistance accelerated test.

However, the UV irradiation intensity of the samples in these testers is generally about 6 mW per 1 cm ^{2 of the} irradiated surface, and it takes about several hundred hours or more to measure and determine the UV deterioration characteristics equivalent to one year of sunlight. Was needed.

In addition, conventionally, a method of subjecting all the samples of each lot to a 100% test is generally performed, so that it takes a long time to measure and judge the result, which is extremely inefficient. was there.

As a means of solving such a problem, the inventors of the present invention first set a sample before applying it to a weather resistance tester.
For each lot, samples are irradiated with strong ultraviolet rays from a metal halide lamp, for example, ultraviolet rays with an intensity of about 50 mW or more per 1 cm ^{2 of the} surface to be irradiated, and it is possible to judge the deterioration of ultraviolet rays in an extremely short time, for example, 1/10 or less of the conventional time. So to speak, a press tester for performing a pre-test of a weather resistance test has been proposed (see JP-A-60-117128 and JP-A-60-117129).

Incidentally, it is desired that the weather resistance test is performed under physical conditions under which samples such as plastics and paints are exposed in actual use. In particular, the sample at night is not simply exposed to sunlight and is not only exposed to low temperatures, but also tends to form dew due to the low temperatures.

Therefore, it is preferable to apply such a dew condition to the weather resistance test or the pre-test in that a result correlated with outdoor natural deterioration is obtained.

Conventionally, as a method of giving such a condensation condition to a sample, for example, Japanese Patent Publication No. 55-13541 proposes a method of immersing the sample in water. However, such flooding methods can never reveal actual condensation conditions,
It cannot be replaced.

On the other hand, the inventors of the present invention consider adjusting the temperature of the sample and the temperature and humidity of the ambient air of the sample as a method of applying an actual dew condensation state to the sample, and An adjusting means is provided, and a humidifier is arranged in the compartment in which the sample mounting table is arranged, and specific operating conditions are given to them through the control means, so that the temperature of the sample is controlled during the off period of the ultraviolet irradiation source. It has been proposed to lower the dew point to below the dew point so that a dew condensation state close to natural dew condensation can be imparted to a sample (Japanese Patent Laid-Open No. 62-297744).
No.).

Further, as means for forming dew on the surface of the sample, a method of spraying cooling water on the back surface of the sample or cooling the sample with an electronic cooling element is disclosed in Japanese Patent Application Laid-Open No. 58-90146.

By the way, in the accelerated weather resistance test of irradiating with ultraviolet rays, when the above-mentioned dew condensation process is added, a speckle pattern appears on the sample surface as the test time elapses, and a significant color change on the sample surface may appear. found. In particular, it was found that when this dew condensation process was added to the accelerated weathering test method having a large ultraviolet irradiation intensity as described above, this phenomenon remarkably appeared.

Such a spot pattern and a large color change are phenomena that do not appear when the sample is left naturally outdoors, and therefore this phenomenon is extremely inconvenient when considering the correlation between natural deterioration and the results of weathering test. It is something.

The cause of such spots is that impurities contained in the dew condensation formed on the sample surface in the dew condensation process, or substances extracted from the sample due to dew condensation formed on the sample surface adhere to the sample surface It is considered that in the ultraviolet irradiation process after the process, these surface deposits are burned on the sample surface due to the lens action of the remaining dew condensation, etc.

In order to prevent the occurrence of such spots, the inventors of the present invention previously disclosed in Japanese Patent Application No. 63-131627 a process of irradiating a sample with ultraviolet rays by an artificial light source and a process of dew condensation on the surface of the sample. In a weather resistance test method including a step of irradiating the sample again with ultraviolet light after the dew condensation step, at least a step of irradiating ultraviolet rays and then dew condensation on the surface of the sample and a step of irradiating ultraviolet ray again after the dew condensation step Between,
A weather resistance test method was proposed in which a process of cleaning the sample surface with a cleaning material was added.

According to this weather resistance test method, at least a step of cleaning the sample surface with a cleaning material must be added between the step of irradiating ultraviolet rays and then dew condensation on the sample surface and the step of irradiating ultraviolet rays again after the dew condensation step. As a result, impurities attached to the sample surface in the dew condensation process or substances extracted on the sample surface are washed away with a cleaning material, so these substances etc. remain attached to the sample surface and are baked in the next UV irradiation process. Therefore, it is possible to effectively prevent the generation of the spot pattern on the sample surface, and to prevent a large color change on the sample surface accordingly.

[Problems to be Solved by the Invention]

However, according to the previously proposed weather resistance test method, the generation of spot patterns on the sample surface and the significant color change on the sample surface are effectively prevented. Since this is an extremely severe weather resistance test conducted in a short time, only the sample surface is apt to be rapidly affected and deteriorated. As a result, water does not penetrate sufficiently into the sample during the dew condensation process, or the inside of the sample contains additives such as plasticizers, stabilizers, antioxidants, UV absorbers and antistatic agents. Is not sufficient, and only the surface layer deteriorates, and changes inside the sample are difficult to promote. In particular, some samples with poor heat resistance such as PVC cannot obtain a subtle deterioration state due to a sudden surface change, and can not obtain satisfactory results in terms of correlation with outdoor exposure test results. Turned out to be.

The following additives are generally used in plastics and paints.

Heat stabilizer Organotin stabilizer (dioctyl tin laurate, dibutyl tin malate, etc.) Calcium stabilizer (calcium stearate, etc.) Barium stabilizer (barium stearate, etc.) Lead stabilizer (tribasic lead sulfate, lead stearate) Epoxy compounds, etc. Antioxidants Phenol-based antioxidants Organic sulfur-based antioxidants Phosphorus-based antioxidants, etc. UV absorbers hydroxybenzophenone-based benzotriazole-based salicylate-based plasticizers Phthalate-based (DBP, DOP, DHP) Etc.) Phosphate ester type (TCP, TPP etc.) Trimellitic acid ester type (TOTM etc.) Epoxy compound type Polyester type etc. Light stabilizer Hindered amine type Flame retardant Halogen type, Phosphorus type etc. Antistatic agent Anion type, Nonion type, Cation type The present invention has been proposed above. It was made in order to solve the above problems in the weather resistance test method, which suppresses rapid surface deterioration, promotes mild deterioration to the inside, and allows subtle changes at the beginning of the test and natural deterioration. It is an object of the present invention to provide a weather resistance test method capable of obtaining test results with extremely high correlation.

[Means and Actions for Solving the Problems]

In order to solve the above-mentioned problems, the present invention includes a step of irradiating a sample with ultraviolet light by an artificial light source, a step of dew condensation on the surface of the sample, and a step of irradiating the sample again with ultraviolet light after the dew condensation step. In the weather resistance test method, at least, between the step of irradiating ultraviolet rays and then dew condensation on the surface of the sample and the step of irradiating ultraviolet rays again after the dew condensation step,
The method is characterized in that a step of cleaning the sample surface with a cleaning material and a step of maintaining the sample in a constant temperature and humidity without light are added.

Thus, in addition to the washing process, by adding a process of holding the sample at a constant temperature and humidity without light (hereinafter referred to as a rest process), the content of the sample can be approximated to a natural condition, which is abrupt. Not only the deterioration of the surface is prevented, but also moisture and permeation into the sample and bleeding of various additives are promoted during the resting process, which causes deterioration to the inside by combining with other test processes. Accelerated and highly correlated test results with subtle changes early in the test.

〔Example〕

Examples of the present invention will be described below. FIG. 1 is a schematic diagram showing a configuration example of a test apparatus used for carrying out the weather resistance test method according to the present invention, and 1 is a light source, for example, a considerably large energy in a wavelength range of 250 to 550 nm. With a metal halide lamp that has a wavelength range of substantially 300
It consists of a filter that narrows down to ~ 450 nm and a water cooling jacket. The light source 1 is housed inside a reflector composed of a dome-shaped main reflector 2 for parallel light and an auxiliary reflector 3 for parallel light. A shield plate 4 made of quartz glass transmits ultraviolet rays and blocks the sample chamber 5 and the light source unit.

Reference numeral 7 denotes a sample stage arranged in the sample chamber 5. The sample stage 7 has a sample 6 attached thereto, and is provided with a temperature adjusting unit such as a water cooling unit or an electronic cooling unit (not shown).
A blowing nozzle 8 blows air having a predetermined temperature to the sample 6 mounted on the sample table 7 to maintain the sample 6 at the predetermined temperature. Reference numeral 9 denotes a humidifying tank for humidifying the sample chamber 5, which is provided with a heater 10 for heating. 11a, 11b
Is a spray nozzle for spraying a cleaning material toward the sample 6 attached to the sample table 7. As a cleaning material,
Water, a surfactant, water containing air, alcohol and the like are used.

The sample table 7 is arranged, for example, at an angle of about 15 ° so that the cleaning material sprayed from the spray nozzles 11a and 11b flows down without stagnation, and accordingly, the light source unit is also inclined and attached to the sample chamber 5. ing. The sample chamber 5 is also provided with a temperature detector, a humidity detector, etc., which are not shown. In the figure, 12 is a spray nozzle pipe, 13 is a solenoid valve,
Reference numeral 14 is a cleaning material supply port, and 15 is a control device for controlling the operations of the light source 1, the air blow nozzle 8, the heater 10 of the humidifying tank 9, the solenoid valve 13, the temperature adjusting means of the sample table 7 and the like according to a predetermined process.

In order to perform the weather resistance test according to the present invention using the weather resistance test apparatus configured as described above, the sample 6 is first placed on the sample table 7.
And is irradiated with ultraviolet rays for a fixed time (for example, 4 hours) by turning on the light source 1. In this case, the sample 6 is maintained at a constant temperature (40 to 100 ° C. ± 1.0 ° C.) by the air injected from the blowing nozzle 8 based on a detection signal of a temperature detector (not shown). Next, when the irradiation of the ultraviolet rays is interrupted by the turning-off operation of the light source 1, the temperature of the sample stage 7 is lowered to a predetermined temperature below the dew point by the temperature adjusting means (not shown) provided in the sample stage 7 based on the detection signal of the temperature detector. Humidification tank 9
Is heated to generate steam, and the sample moisture 5 is humidified to a predetermined humidity. As a result, dew condensation occurs on the surface of the sample 6 held on the sample table 7.

After this dew condensation state is continued for a certain time (for example, about 1 hour), the spray nozzles 11a and 11b that operate the solenoid valve 13 are operated to inject the cleaning material toward the sample 6 to remove the dew condensation and the sample surface. To wash. Then, with the light source 1 turned off, the temperature (for example, 45 ° C) and humidity (for example, 95%)
RH) and the rest state is continued for a predetermined time (for example, 5 hours). Then, the light source 1 is turned on again to irradiate the sample 6 with ultraviolet rays. Hereinafter, these steps are repeatedly performed.

By performing the weather resistance test in this manner, the sample is provided with a state very close to the dew condensation state when left outdoors outdoors and the state at night, and by adding a washing process, a spot pattern on the sample surface is formed. Occurrence,
Since a large color change on the surface of the sample is prevented and deterioration of the inside of the sample is promoted, it is possible to obtain a weather resistance test result having a very high correlation with a subtle change in the initial stage of the test and natural deterioration.

In the above embodiment, the cleaning process is shown as being added between the dew condensation process and the next ultraviolet irradiation process, but this cleaning process should be added before the next dew condensation process after ultraviolet irradiation. However, in this case, it is possible to more effectively prevent the generation of the spot pattern and the large color change. Furthermore, it is also effective to add this cleaning process during the condensation process.

Also, the temperature condition in the rest process depends on the sample.
The setting conditions can be appropriately changed within the range of temperature of 30 to 85 ° C and humidity of 20 to 100% RH. In addition, the insertion time of the rest process in the combination cycle of each process can be appropriately selected, and the combination cycle can be 4 to.
It can be arbitrarily selected within the range of 50 hours, and the most natural condition can be selected and set by an experiment.

Further, in the configuration example of the test apparatus, two spray nozzles for injecting the cleaning material are provided on the left and right above the sample, but the number and arrangement position of the spray nozzles are not limited to this, and they are not limited to the sample table. It can be appropriately set according to the shape, size, and the like. As means for cleaning the sample, means for spraying high temperature steam onto the surface of the sample for cleaning can be used, and an ultrasonic cleaner or the like can also be used.

Next, in order to confirm the effect of the weather resistance test method according to the present invention, the result of a test example carried out together with the conventional weather resistance test method will be described.

(1) Test conditions of the present invention Light source used: metal halide lamp 4 kW Irradiation wavelength: 300 to 450 nm Black panel temperature (at ultraviolet irradiation): 63 ° C. ± 3 ° C. Sample surface ultraviolet intensity: 100 ± 5 mW / cm ² Humidity in sample chamber : 95% RH or more Black panel temperature with dew condensation: 30 ℃ ± 1 ℃ Humidity of sample room at rest: 95% RH or more Black panel temperature at rest: 45 ℃ ± 2 ℃ Cleaning time: 30 seconds after irradiation and 30 after dew condensation Second Cleaning material: Ion-exchanged water Cleaning material temperature: 20 ° C Cleaning material injection rate: 9cc per 1 cm ² of sample surface Cleaning material injection pressure: 1.5 kg / cm ² Test cycle: UV irradiation 4 hours, condensation 1 hour, rest 5 hours (2) Test conditions for conventional example (Sunshine weather meter) Light source used: Sunshine carbon arc lamp Irradiation wavelength: 280 to 1400 nm Black panel temperature: 63 ° C ± 3 ° C UV intensity on sample surface: 5 mW / cm ² (3) Conventional example 2 (Xenon weather meter) test conditions Light source used Xenon arc lamp 3.5kW irradiation wavelength: 300～1400Nm black panel temperature: 63 ° C. ± 3 ° C. specimen surface UV intensity: 2.3mW / cm ² (4) Conventional Example 3 (having no washing process alone was added rest process) of the test Conditions: Light source used, condensation conditions, cleaning conditions, UV irradiation / condensation cycle, etc. are the same as the test conditions of the present invention. (5) Test conditions for Reference Example 1 (outdoor exposure) Period: May 1987 to 1988 4 12 months until March: Matsudo City, Chiba Prefecture The sample used was hard vinyl chloride prepared under the following sample preparation conditions.

Sample preparation conditions (a) Composition (unit: PHR) PVC (degree of polymerization = 1100) 100 Tribase 1.0 Stearate 1.5 Dibasic lead stearate 0.3 Calcium stearate 0.3 Calcium carbonate 8.75 Titanium oxide 0.2 Carbon black 1.0 (b) Molding Conditions The powder mixed in the above formulation is kneaded on a hot roll at 160 to 170 ° C for 5 minutes, and the bare sheet obtained is 190 to 195.
The sample was pressed at 10 ° C. for 10 minutes, and after cooling, a sample was prepared as a sheet of about 1.0 mm.

The sample prepared as described above is subjected to each test under the above test conditions, and the 60 ° gloss retention (this is for measuring the change in the reflectance of the sample surface), CIE1976
L ^* , a ^* , b ^* L ^* value (this is for measuring the change in lightness of the sample surface) in the color display by the spatial color system, b ^* value (this is the chromaticity of the sample surface And the color difference ΔE ^* (which is for measuring the change in hue on the sample surface) obtained from this color system. , Shown in FIGS.

Curve a in FIG. 2 shows the change in the gloss retention in the outdoor exposure test.
%, But has not changed much since then. On the other hand, in the sunshine weather meter (conventional example 1),
As shown by the curve b in FIG. 3, the same tendency as in the outdoor exposure test is shown, and the xenon weather meter (conventional example 2) shows a substantially linear change as shown by the curve c in FIG. In any case, by the time the gross retention rate drops to 20%,
It turns out that it needs about 600-800 hours.

On the other hand, as shown by the curve d in FIG. 4, in the case of the conventional example 3 in which only the washing process is added, it decreases to 20% or less before reaching 50 hours. As a result, the method according to Conventional Example 3 can bring the gloss retention rate of the sample to a deteriorated state of about 8 months at the time of outdoor exposure in a test time of about 1/10 or less that of Conventional Examples 1 and 2. I understand. However, in the method according to Conventional Example 3, the gloss retention rate tends to continue to decrease even after the test period of 50 hours, which is slightly different from the outdoor exposure test. On the other hand, in the method according to the present invention, as shown by the curve e in the figure, the degree of decrease is slightly small, but the test period hardly changes after 60 hours, and a test result extremely similar to the outdoor exposure test is obtained. You can see that

Next, as shown by the curve a in FIG. 5, the color difference ΔE ^* increases almost linearly in the case of outdoor exposure,
After a month, the ΔE ^* value reached 20, and thereafter a tendency to sharply increase was observed.
Even at 000 hours, as shown by the curves b and c, the saturated state is reached and the ΔE ^* value has not reached 10.

On the other hand, as shown by the curve d in FIG.
It reaches about 15 in time, and shows a rapid rising tendency with the passage of time, but it can be seen that there is a rapid change in the initial stage of the test and a state in which the change does not progress during the test. On the other hand, in the method according to the present invention, as shown by the curve e in the same figure, as it reaches about 20 at 50 hours, the initial change is gradual and changes linearly with the lapse of test time as in the outdoor exposure test. , Shows a similar trend.

Next, the measurement results of the L ^* value are shown in FIGS. 7 (A), (B),
It shows in (C). The curve a in Fig. 7 (A) shows the change at the time of outdoor exposure, and shows a gradual increase with time.
In months the L ^* value has reached 70. On the other hand, as shown by the curves b and c in FIG. 7 (B), in the conventional examples 1 and 2, there is little change or a slight decrease even after the test time has elapsed, and the tendency is completely different from the outdoor exposure test. Is shown.

On the other hand, as shown by the curve d in FIG.
Then, the L ^* value once decreased with the passage of time, but started to rise again, and reached a state close to the deterioration state at 12 months of outdoor exposure in a short time of 50 hours. On the other hand, in the method according to the present invention, as shown by the curve e in the figure, it shows a gradual increase tendency with almost no decrease with the passage of time, and the L ^* value reaches almost 70 at 80 hours, which is extremely close to the outdoor exposure test. It can be seen that similar test results are obtained.

Now it is described results of measurement of the b ^* value, as shown in Figure 8 curve a, in the case of outdoor exposure test initially, b ^*
The value shows a (-) value (blue), but once changes to a value close to 0, and shows a tendency to increase again to a higher (-) value. On the other hand, as shown by the curves b and c in the figure, both of the conventional examples 1 and 2 change to the (+) value (yellow), and the sample surface shows a tendency to increase the yellowing degree with the passage of time. I have.

On the other hand, as shown by the curve d in FIG.
^{* The} value temporarily changes to (+) value and turns yellow, but returns to (-) value again at 504 hours, showing a tendency similar to outdoor exposure.
On the other hand, in the method according to the present invention, the curve e in FIG.
As shown in, the degree of yellowing at the beginning of the test is extremely small, and the rapid initial change is alleviated as compared with Conventional Example 3,
It can be seen that the outdoor exposure test shows a similar tendency.

When the weather resistance test is carried out by the method of the present invention from the above test data, etc., compared with the weather resistance test method in which only the previously proposed cleaning process is added, the rapid initial change is alleviated, and the time is short. It was confirmed that the test result more closely resembled the deterioration condition after long-term outdoor exposure, and therefore it was confirmed that the test result having higher correlation with the natural deterioration can be obtained.

In the experiment by each of the above test methods, the one using a hard vinyl chloride plate was shown as a sample, but also when using a soft vinyl chloride plate having a different material and surface color, an acrylic coating plate, etc. as a sample, The test result according to the present invention and the test result according to Conventional Example 3 have almost the same results, and according to the weather resistance test method according to the present invention, generation of a spot pattern on the sample surface and significant coloration of the sample surface. Not only can changes be effectively prevented, but rapid surface deterioration can also be prevented to promote deterioration to the inside of the sample, and sudden initial changes can be mitigated to obtain weather resistance test results that are highly correlated with natural deterioration. It was confirmed to be easy to obtain.

In the test example of the present invention, as an artificial light source, a wavelength range of 250 to 550 nm is combined with a metal halide lamp having a filter of substantially narrowing the wavelength range to 300 to 450 nm.
The test was performed using a light source such that the UV intensity on one surface was 100 ± 5 mW / cm ² , but for example, several tens mW / cm ²
Similar test results can be obtained even when an artificial light source that emits a light source that contains ultraviolet light having the above intensity and that also contains visible light and / or infrared light is used.

〔The invention's effect〕

As described above based on the examples, according to the weather resistance test method of the present invention, at least between the step of irradiating ultraviolet rays and then dew condensation on the sample surface and the step of irradiating ultraviolet rays again after the dew condensation step. Since the process of cleaning the sample surface with the cleaning material and the rest process without light are added, not only the generation of the spot pattern on the sample surface and the significant color change of the sample surface can be effectively prevented, but also In addition, it is possible to easily obtain a weather resistance test result that has a very good correlation with natural deterioration by preventing the rapid change and deterioration, promoting the deterioration up to the inside of the sample, and relaxing the sudden initial change.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of a test apparatus used for carrying out the weather resistance test method according to the present invention, FIG. 2 is a view showing a change in gloss retention rate in an outdoor exposure test, and FIG. ,
The figure which shows the change of the gloss retention rate by the test of the prior art examples 1 and 2, FIG. 4 is a figure which shows the change of the gloss retention rate by the test of this invention and the prior art example 3, FIG. 5 is outdoor exposure, the conventional example. 1
And shows the change of the color difference Delta] E ^* according to the second test, Figure 6 is a graph showing changes in color difference Delta] E ^* by the test of the present invention and the conventional example 3, FIG. 7 (A) is L by outdoor exposure test Figure showing changes in ^* value, Figure 7 (B) shows changes in L ^* value by the tests of Conventional Examples 1 and 2, and Figure 7 (C) shows tests by the present invention and Conventional Example 3. FIG. 8 is a diagram showing changes in L ^* value, FIG. 8 is a diagram showing changes in b ^* value by outdoor exposure and tests of Conventional Examples 1 and 2, and FIG. 9 is b by each test of the present invention and Conventional Example 3. ^* It is a figure which shows the change of a value. In the figure, 1 is a light source, 2 is a main reflector, 3 is an auxiliary reflector, 4 is a shield plate, 5 is a sample chamber, 6 is a sample, 7 is a sample table, 8 is a blowing nozzle, 9 is a humidifying tank, and 10 is Heater for heating,
11a and 11b are spray nozzles, 12 is piping, 13 is a solenoid valve, 14
Denotes a cleaning material supply port, and 15 denotes a control device.

Claims (1)

[Claims] 1. A weather resistance test method comprising: a step of irradiating a sample with ultraviolet light by an artificial light source; a step of dew condensation on the surface of the sample; and a step of irradiating the sample again with ultraviolet light after the dew condensation step. , Between the step of irradiating ultraviolet rays and then dew condensation on the surface of the sample and the step of irradiating ultraviolet rays again after the dew condensation step, a step of washing the sample surface with a cleaning material, and a sample without light and at a constant temperature and humidity. A method for testing weather resistance, characterized by adding a process of maintaining the state.